This invention relates to a method and apparatus for treating a metal melt, for example, a steel melt to be refined by the addition to it of lime, alloying materials, ore concentrates, pulverized coal or mixtures thereof, and possibly other materials, which do not, through reacting with the melt, add heat to the melt.
The Fredrikson et al U.S. application Ser. No. 499,759, filed Aug. 22, 1974, issued July 27, 1976 as U.S. Pat. No. 3,971,547 and assigned to the assignee of the present application, discloses a method and apparatus wherein such materials, in a fluent condition, as by being granulated, are pressure-injected into a melt below the upper surface of the melt, with the melt contained in a convertor-like vessel which can be tilted between substantially vertical and horizontal positions and having a tapping hole in its side which is downward when the vessel is horizontal. The vessel has an open top for initially charging it with the melt and it has a lower portion or bottom in which a channel-type inductor is positioned with the channel extending diagonally downwardly away from that side of the vessel which is lowermost when the vessel is horizontal, so that whether the vessel is vertically positioned or horizontally positioned, sump metal can always be retained in the inductor's channel. For the injection of the fluent material, a nozzle or tuyere is positioned in the lower portion of the furnace pointing upwardly at approximately the focus of the melt currents characteristically formed by the melt circulating in the inductor's channel in an electrodynamic manner. This arrangement is for the purpose of preventing the fluent materials, usually in the form of solid particles, from getting into the inductor's channel, and causing trouble there.
The above described apparatus, has the disadvantage that the electric power which can be supplied to the inductor, is limited; the amount of heat that can be added to the melt in the vessel to keep it at a proper temperature during the injection of the fluent material, is consequently limited,. This is due to the size limitations of channel-type inductors imposed by considerations of initial construction expense and servicing problems. For practical reasons, it is not desirable to provide the vessel with more than two of the inductors.
In the same field, the purpose of the present invention is to provide a way to avoid the limitations described above, while retaining the advantages of the tilting convertor-like vessel which can be vertically positioned for charging with the melt and for the injection of the fluent materials, and which, after the treatment, can be tilted to its horizontal position for tapping through the tap hole which is in the then downward side of the vessel. As disclosed by the aforesaid Fredrikson et al application, it is desirable that the tilting vessel have a removable cover for its top, which is applied to the vessel's top after the melt charging and which has a gas outlet so that gases resulting from reactions between the injected materials and the melt, can be collected and carried away from the vicinity of the vessel.